Blood pressure influences the occurrence of complex ventricular arrhythmia in hemodialysis patients

Lethal ventricular arrhythmia can be prevented by adjusting the dialysate potassium concentration and the use of anti-arrhythmic agents: a case report and literature review

Background

Hypokalemia is common in patients with malnutrition undergoing hemodialysis and is often involved in the development of lethal arrhythmia. Moreover, hemodialysis therapy decreases the serum potassium concentration due to potassium removal to the dialysate. However, it is difficult to adjust the dialysate potassium concentration owing to the use of the central dialysate delivery system in Japan. Here, we have presented a case undergoing hemodialysis with dialysate potassium concentration adjustment to prevent ventricular arrhythmia.

Case presentation

A 56-year-old man with Emery-Dreifuss muscular dystrophy and chronic heart failure was admitted to our hospital and needed subsequent hemodialysis therapy due to renal dysfunction. During hemodialysis, the cardiac resynchronization therapy defibrillator was activated to the treatment of his lethal ventricular arrhythmia. Decreases in serum potassium concentration after hemodialysis and changes in serum potassium concentration during HD were considered the causes of lethal ventricular arrythmia. Therefore, along with using anti-arrhythmic agents, the dialysate potassium concentration was increased from 2.0 to 3.5 mEq/L to minimize changes in the serum potassium concentration during hemodialysis. Post-dialysis hypokalemia disappeared and these changes during hemodialysis were minimized, and no lethal ventricular arrhythmia occurred thereafter.

Conclusions

In this case, we prevented lethal arrhythmia by maintaining the serum potassium concentration by increasing the dialysate potassium concentration, in addition to the use of anti-arrhythmic agents. In the acute phase of patients with frequent lethal arrhythmia undergoing hemodialysis, an increase in dialysate potassium concentration may be an effective method for preventing arrhythmogenic complications.

Asymptomatic Ventricular Arrhythmia and Clinical Outcomes in Chronic Kidney Disease: A Pilot Study

BACKGROUND/AIMS

Ventricular arrhythmia is associated with increased risk of cardiovascular events and death in the general population. Sudden death is a leading cause of death in end-stage renal disease. We aimed at evaluating the effects of ventricular arrhythmia on clinical outcomes in patients with earlier stages of chronic kidney disease (CKD).

METHODS

In a prospective study of 109 nondialyzed CKD patients (estimated glomerular filtration rate 34.8 ± 16.1 ml/min/1.73 m², 57 ± 11.4 years, 61% male, 24% diabetics), we tested the hypothesis that the presence of subclinical complex ventricular arrhythmia, assessed by 24-hour electrocardiogram, is associated with increased risks of cardiovascular events, hospitalization, and death and with their composite outcome during 24 months of follow-up. Complex ventricular arrhythmia was defined as the presence of multifocal ventricular extrasystoles, paired ventricular extrasystoles, nonsustained ventricular tachycardia, or R wave over T wave.

RESULTS

We identified complex ventricular arrhythmia in 14% of participants at baseline. During follow-up, 11 cardiovascular events, 15 hospitalizations, and 4 deaths occurred. The presence of complex ventricular arrhythmia was associated with cardiovascular events (p < 0.001), hospitalization (p = 0.018), mortality (p < 0.001), and the composite outcome (p < 0.001). In multivariate Cox regression analysis, adjusting for demographic characteristics, complex ventricular arrhythmia was associated with increased risk of the composite outcome (HR 4.40; 95% CI 1.60-12.12; p = 0.004).

CONCLUSION

In this pilot study, the presence of asymptomatic complex ventricular arrhythmia was associated with poor clinical outcomes in nondialyzed CKD patients.

Predictors of Arrhythmic Events Detected by Implantable Loop Recorders in Renal Transplant Candidates

BACKGROUND

The recording of arrhythmic events (AE) in renal transplant candidates (RTCs) undergoing dialysis is limited by conventional electrocardiography. However, continuous cardiac rhythm monitoring seems to be more appropriate due to automatic detection of arrhythmia, but this method has not been used.

OBJECTIVE

We aimed to investigate the incidence and predictors of AE in RTCs using an implantable loop recorder (ILR).

METHODS

A prospective observational study conducted from June 2009 to January 2011 included 100 consecutive ambulatory RTCs who underwent ILR and were followed-up for at least 1 year. Multivariate logistic regression was applied to define predictors of AE.

RESULTS

During a mean follow-up of 424 ± 127 days, AE could be detected in 98% of patients, and 92% had more than one type of arrhythmia, with most considered potentially not serious. Sustained atrial tachycardia and atrial fibrillation occurred in 7% and 13% of patients, respectively, and bradyarrhythmia and non-sustained or sustained ventricular tachycardia (VT) occurred in 25% and 57%, respectively. There were 18 deaths, of which 7 were sudden cardiac events: 3 bradyarrhythmias, 1 ventricular fibrillation, 1 myocardial infarction, and 2 undetermined. The presence of a long QTc (odds ratio [OR] = 7.28; 95% confidence interval [CI], 2.01-26.35; p = 0.002), and the duration of the PR interval (OR = 1.05; 95% CI, 1.02-1.08; p < 0.001) were independently associated with bradyarrhythmias. Left ventricular dilatation (LVD) was independently associated with non-sustained VT (OR = 2.83; 95% CI, 1.01-7.96; p = 0.041).

CONCLUSIONS

In medium-term follow-up of RTCs, ILR helped detect a high incidence of AE, most of which did not have clinical relevance. The PR interval and presence of long QTc were predictive of bradyarrhythmias, whereas LVD was predictive of non-sustained VT.

Assessment and management of hypertension in patients on dialysis

Hypertension is common, difficult to diagnose, and poorly controlled among patients with ESRD. However, controversy surrounds the diagnosis and treatment of hypertension. Here, we describe the diagnosis, epidemiology, and management of hypertension in dialysis patients, and examine the data sparking debate over appropriate methods for diagnosing and treating hypertension. Furthermore, we consider the issues uniquely related to hypertension in pediatric dialysis patients. Future clinical trials designed to clarify the controversial results discussed here should lead to the implementation of diagnostic and therapeutic techniques that improve long-term cardiovascular outcomes in patients with ESRD.

Sailing between Scylla and Charybdis: the high serum K-low dialysate K quandary

In HD patients, the optimal choice of dialysate K concentration is of paramount importance. Recent large observational studies have documented an association between low dialysate K concentration (< 2 or even <3 mEq/L) and a higher risk of sudden death. In this review, we first briefly discuss the available data concerning the link between hypokalemia and negative outcomes in non-CKD populations, especially after an acute myocardial infarction or in congestive heart failure. We next review the pathophysiology of the arrhythmogenic effect related to K fluxes during HD and discuss the dialytic strategies aiming at making potassium fall more gradual and thus at reducing the electrical disturbances triggered by the HD session. We conclude with practical recommendations regarding the optimal choice of K bath and the importance of more frequent monitoring of serum K in some clinical scenarios.

End-Stage Renal Disease and Sudden Cardiac Death

Patients with end-stage renal disease (ESRD) are at a high risk for sudden cardiac death (SCD). SCD is the most common cause of death in this population and, as in the general population, ventricular arrhythmias seem to be the most common cause of SCD. The increased risk of SCD in ESRD is likely due to factors that are unique to the metabolic derangements associated with this state, as well as the increased prevalence of traditional risk factors. Despite this, the evidence base for the assessment and management of SCD in these patients is limited. This article reviews the current data on underlying risk factors for SCD in patients with ESRD, the role of common medical and device-based therapies for the prevention and treatment of SCD, and the applicability of common methods of risk stratification to patients with ESRD.

[Technical advances in haemodialysis]

Survival improvement of our haemodialysis patients is partly due to technologic improvement of the dialysis therapy. High permeability membranes and bicarbonate dialysate were the most relevant of past decades. What are the present technologic innovations that will provide clinical benefit? Acetate-free biofiltration, biofeedback systems, better haemodiafiltration techniques and techniques with adsorption could be part of them.

The association between blood pressure and mortality in ESRD-not different from the general population?

Hypertension (HTN) is a traditional cardiovascular risk factor and is prevalent in end-stage renal disease (ESRD). There are no adequately powered prospective studies that explore the natural history and outcomes of HTN and blood pressure management in ESRD. Observational studies have not uniformly showed a relationship between HTN and mortality risk in this population. Furthermore, many studies paradoxically show an increased risk of death associated with low and "normal" blood pressure (BP), sometimes referred to as "reverse epidemiology." We review findings from observational studies specifically performed in ESRD and provide an alternative interpretation-that patients with kidney disease on dialysis therapy are indeed different from the general population. At minimum, these differences may be based on the prevalence of cardiovascular morbidity, specifically the excessive prevalence of congestive heart failure. However, there are other reasons for ESRD patients, especially those on hemodialysis, to exhibit differential effects with regard to blood pressure and outcomes. We explore the implications of available observational evidence and recommend studies that elucidate the differences between ESRD and the general population. Because of the higher mortality risk associated with low or "normal" BP, diagnostic and therapeutic options and strategies for ESRD patients whose BP falls within "goal" should be addressed in future iterations of clinical practice guidelines. These strategies may include assessment of cardiac function and careful attention to achieving optimal fluid balance.

Practical ways to deal with the high burden of cardiovascular disease in hemodialysis patients

Cardiovascular disease is the main cause of death among hemodialysis patients. Although uremia by itself may be considered to be a cardiovascular risk factor, a significant proportion of dialysis patients die because of cardiovascular disease not directly attributable to uremia. Indeed, many of the cardiovascular diseases and cardiovascular risk factors in these patients are common to those occurring in the general population and are amenable to intervention. Lack of proper medical care during the early stages of renal insufficiency and present-day dialysis routines, by failing to correct hypertension, hypervolemia and left ventricular hypertrophy in many patients, may also add to the cardiovascular burden. The author suggests that, in addition to early treatment and referral to a specialist, chronic renal failure patients should undergo intensive cardiovascular screening and treatment, and correction of cardiovascular risk factors based on guidelines established for the general population.

Optimal composition of the dialysate, with emphasis on its influence on blood pressure

Introduction. From the beginning of the dialysis era, the most appropriate composition of the dialysate has been one of the central topics in the delivery of dialysis treatment.

METHODS

A discussion is employed to achieve a consensus on key points relating to the composition of the dialysate, focusing on the relationships with blood pressure behaviour.

RESULTS

Sodium balance is the cornerstone of intra-dialysis cardiovascular stability and good inter-dialysis blood pressure control. Hypernatric dialysis carries the risk of positive sodium balance, with the consequent possibility of the worsening sense of thirst and hypertension. Conversely, hyponatric dialysis may lead to negative sodium balance, with the possibility of intra-dialysis cardiovascular instability and 'disequilibrium' symptoms including fatigue, muscle cramps and headache. The goal is to remove with dialysis the exact amount of sodium that has accumulated in the inter-dialysis interval. The conductivity kinetic model is applicable on-line at each dialysis session and has been proved to be able to improve intra-dialytic cardiovascular stability in hypotension-prone patients. Therefore, it should be regarded as a promising tool to be implemented in everyday clinical practice. Serum potassium concentration and variations during dialysis treatment certainly play a role in the genesis of cardiac arrhythmia. Potassium profiling, with a constant gradient between plasma and dialysate, should be implemented in clinical practice to minimize the arrhythmogenic potential of dialysis. Calcium plays a role both in myocardial contractility and in peripheral vascular resistance. Therefore, an increase in dialysate calcium concentration may be useful in cardiac compromised hypotension-prone patients. Acid-buffering by means of base supplementation is one of the major roles of dialysis. Bicarbonate concentration in the dialysate should be personalized in order to reach a midweek pre-dialysis serum bicarbonate concentration of 22 mmol/l. The role of convective dialysis techniques in cardiovascular stability is still under debate. It has been demonstrated that dialysate temperature and sodium balance play a role and this should be taken into account. Whether removal of vasoactive, middle-sized compounds by convection plays an independent role in improving cardiovascular stability is still uncertain.

CONCLUSIONS

The prescription of dialysis fluid is moving from a pre-fixed, standard dialysate solution to individualization of electrolyte and buffer composition, not only during the dialysis session, but also within the same session (profiling) in order to provide patients with an optimal blood purification coupled with a high degree of tolerability.

HYPERTENSION IN HEMODIALYSIS PATIENTS: Cardiac Consequences of Hypertension in Hemodialysis Patients

Hypertension in end-stage renal disease (ESRD) is an important risk factor for left ventricular hypertrophy (LVH), cardiac failure, coronary artery disease (CAD), and arrhythmia. LVH is generally considered an integrator of the long-term effects of hypertension and other cardiovascular (CV) risk factors and represents the strongest predictor of adverse CV outcomes in ESRD patients. The risk of heart failure is higher in patients with a history of hypertensive renal disease than in those with other diagnoses. Both coronary heart disease (CHD) and LVH predict congestive heart failure, which is often the ultimate cause of death in patients with cardiac ischemia or LVH. A history of long-standing hypertension is associated with ischemic heart disease both in cross-sectional and prospective studies in ESRD. Atrial fibrillation and ventricular arrhythmias are highly prevalent in dialysis patients and are implicated in mortality and sudden death in this population. Despite the lack of evidence from randomized controlled trials, it appears reasonable that interventions aimed at curbing the high CV mortality of ESRD should be targeted to both hypertension and LVH.

Assessment of blood pressure in hemodialysis patients

It is self-evident that accurate measurement of blood pressure (BP) is essential for the diagnosis and treatment of hypertension. Patients on hemodialysis typically do not have their BP measured under standardized conditions, a source of error in the assessment of their BP. However, their are some unique sources of error involving interdialytic weight gain, occurrence of sleep apnea and consequent nocturnal hypertension, inability to take BP in both arms in patients who have hemodialysis angioaccess in the arm, and the white coat effect in these patients as well. Precise measurement of BP in hemodialysis patients requires interdialytic ambulatory BP monitoring. However, when ambulatory BP monitoring is not possible, BP obtained in the dialysis unit can be used in a qualitative sense for prediction of hypertension in these patients. A 2-week average predialysis BP of greater than 150/85 mmHg or a postdialysis BP of greater than 130/75 mmHg has at least 80% sensitivity in diagnosing hypertension. Specificity of at least 80% can be achieved if predialysis BP of greater than 160/90 mmHg or postdialysis BP of greater than 140/80 mmHg are used. However, poor agreement between hemodialysis unit BP and ambulatory BP precludes their use for the precise prediction of BP. Improving measurement techniques in the dialysis unit, averaging multiple BP values, using 20-minute postdialysis readings, or home BP monitoring can improve BP determination when interdialytic BP monitoring is not possible.

Central and peripheral adaptations to physical training in patients with end-stage renal disease

Renal replacement treatment options are life-saving treatments for patients with end-stage renal disease (ESRD). However, prolonged survival in patients with ESRD is associated with various functional and morphological disorders from almost all systems. Anaemia, deconditioning, cardiac dysfunction. impairment of cardiac autonomic control and skeletal muscle weakness and fatigue, primarily because of 'uraemic' myopathy and neuropathy, are the main predisposing factors for their poor functional ability. Physical training is being recommended as a complementary therapeutic modality. There are generally 3 methods of exercise training applied in patients with ESRD: (i) the supervised outpatient programme that is held in a rehabilitation centre; (ii) a home exercise rehabilitation programme; and (iii) exercise rehabilitation programme during the first hours of the haemodialysis treatment in the renal unit. All the available training data show that the application of an exercise training programme in patients with ESRD enhances their physical fitness. This improvement is due to central and mainly peripheral adaptations. Exercise training in these patients increases aerobic capacity, causes favourable left ventricular functional adaptations, reduces blood pressure in patients with hypertension, modifies other coronary risk factors, increases the cardiac vagal activity and suppresses the incidence of cardiac arrhythmias. Moreover, exercise training has beneficial effects on muscle structural and functional abnormalities. These central and peripheral adaptations to exercise training cause an increase in their functional capacity and offer them achance of a better quality of life. Moreover, exercise training improves exercisee tolerance of renal post-transplant patients.

Hypertension in hemodialysis patients

Hypertension is very common and often poorly controlled in patients undergoing chronic hemodialysis. While high blood pressure has been documented to adversely impact several intermediate outcomes of cardiovascular disease, whether hypertension is an independent risk factor for mortality in this population is not clear. Expansion of extracellular fluid volume is the major pathophysiologic mechanism for the development of hypertension in these patients; however, alterations in other humoral mechanisms also play a significant role. Optimization of volume status is, therefore, the cornerstone of therapy with additional use of antihypertensive medications as needed. Good quality prospective studies are urgently needed to define the measurement techniques and blood pressure goals, and to develop therapeutic strategies for more effective management of hypertension in this high-risk population.

Hyperkalemia in dialysis patients

Serious hyperkalemia is common in patients with end-stage renal disease (ESRD) and accounts for considerable morbidity and death. Mechanisms of extrarenal disposal of potassium (gastrointestinal excretion and cellular uptake) play a crucial role in the defense against hyperkalemia in this population. In this article we review extrarenal potassium homeostasis and its alteration in patients with ESRD. We pay particular attention to the factors that influence the movement of potassium across cell membranes. With that background we discuss the emergency treatment of hyperkalemia in patients with ESRD. We conclude with a review of strategies to reduce the risk of hyperkalemia in this population of patients.

Cardiac arrest and sudden death in dialysis units

BACKGROUND

For patients with end-stage renal disease and their providers, dialysis unit-based cardiac arrest is the most feared complication of hemodialysis. However, relatively little is known regarding its frequency or epidemiology, or whether a fraction of these events could be prevented.

METHODS

To explore clinical correlates of dialysis unit-based cardiac arrest, 400 reported arrests over a nine-month period from October 1998 through June 1999 were reviewed in detail. Clinical characteristics of patients who suffered cardiac arrest were compared with a nationally representative cohort of> 77,000 hemodialysis patients dialyzed at Fresenius Medical Care North America-affiliated facilities.

RESULTS

The cardiac arrest rate was 400 out of 5,744,708, corresponding to a rate of 7 per 100,000 hemodialysis sessions. Cardiac arrest was more frequent during Monday dialysis sessions than on other days of the week. Case patients were nearly twice as likely to have been dialyzed against a 0 or 1.0 mEq/L potassium dialysate on the day of cardiac arrest (17.1 vs. 8.8%). Patients who suffered a cardiac arrest were on average older (66.3 +/- 12.9 vs. 60.2 +/- 15.4 years), more likely to have diabetes (61.8 vs. 46.8%), and more likely to use a catheter for vascular access (34.1 vs. 27.8%) than the general hemodialysis population. Sixteen percent of patients experienced a drop in systolic pressure of 30 mm Hg or more prior to the arrest. Thirty-seven percent of patients who suffered cardiac arrest had been hospitalized within the past 30 days. Sixty percent of patients died within 48 hours of the arrest, including 13% while in the dialysis unit.

CONCLUSIONS

Cardiac arrest is a relatively infrequent but devastating complication of hemodialysis. To reduce the risk of adverse cardiac events on hemodialysis, the dialysate prescription should be evaluated and modified on an ongoing basis, especially following hospitalization in high-risk patients.

Cardiopulmonary events during hemodialysis: effects of dialysis membranes and dialysate buffers

Adverse cardiac and pulmonary events are frequently observed during hemodialysis and contribute to significant morbidity and mortality. The temporal relationship between these events during the intradialytic period has not been well defined. To examine the event rate and timing of silent ischemia, cardiac ectopy, and hypoxemia, we conducted a prospective, single-blind, randomized study of 10 subjects undergoing maintenance hemodialysis with four contiguous combinations of dialysis membranes (cuprammonium or polysulfone) and dialysates (acetate or bicarbonate). The frequency of oxygen desaturation events peaked during the first 2 hours, whereas silent myocardial ischemia and supraventricular ectopies occurred more often in the later hours. Ventricular ectopy occurred steadily throughout the intradialytic period. The combination of acetate dialysis and cuprammonium membrane is associated with the most frequent events. We conclude that cardiopulmonary events can occur frequently during hemodialysis, and the frequency is dependent on the type of dialysis membrane and dialysate buffer used.

Effects of physical training on heart rate variability in patients on hemodialysis

Dysfunction of the cardiac autonomic nervous system is a known complication of end-stage renal disease. The objective of the study was to mainly investigate the effects of physical training on 24-hour vagal cardiac activity in dialysis patients. Sixty chronic uremic patients (mean age 48 +/- 12 years) on maintenance hemodialysis were studied. After initial evaluation, 30 patients (group A) were randomly assigned to a 6-month exercise training program (3/week). The other 30 patients (group B) and 30 nonuremic sedentary persons (group C) remained untrained and were used as controls. Parasympathetic activity was assessed at the beginning and the end of the study noninvasively from 24-hour electrocardiographic ambulatory monitoring by calculating heart rate variability (HRV). HRV index, mean NN interval, and standard deviation NN (SDNN) were measured according to the "triangular method." At baseline HRV index, mean RR, SDNN, and aerobic capacity were significantly reduced in both hemodialysis groups compared with values in group C. Also, 40% of all patients on hemodialysis and 16% of group C had arrhythmias (Lown class >II). Moreover, hemodialysis patients with a more depressed HRV index (<25, n = 37) had a higher incidence of arrhythmias (60%) compared to those with HRV index >25 (p <0.05). Exercise training in group A significantly increased HRV index from 22 +/- 7 to 28 +/- 9 (p <0.05) and SDNN from 0.11 +/- 0.03 to 0.13 +/- 0.04 (p <0.05). Furthermore, fewer patients continued to have an HRV index <25 (by 40%) and arrhythmias (by 33%) compared with baseline data. Training was also associated with a significant improvement in fitness level, as assessed by maximal oxygen consumption (by 41%; p <0.05) and exercise testing duration (by 33%; p <0.05). There was a significant correlation in HRV index and maximal oxygen consumption. No changes were observed in the control groups between baseline and follow-up data. Results demonstrate that physical training in hemodialysis patients augments cardiac vagal activity and decreases vulnerability to arrhythmias.

Baseline variables associated with early death and extended survival on dialysis

Patients who die during the first three months on dialysis are not systematically included in the American and European statistics. In contrast, only a few patients survive more than 10 years on this modality of renal replacement therapy. The factors determining these two extreme forms of outcome are poorly understood. We tested the hypothesis that a few variables, easily obtainable at the initiation of dialysis, would identify those individuals at high and low risk of early death. We retrospectively studied 23 patients who died within 90 days of initiating dialysis and 20 patients who survived more than 10 years. These patients were admitted for dialysis to a Brazilian center between July 1, 1976 and February 28, 1997. The baseline variables assessed which were thought to influence survival, were: age, sex, race, body weight, etiology of renal disease, blood pressure, comorbid conditions, hematocrit and serum electrolytes, albumin, creatinine, urea, and urea/creatinine ratio. Univariate analysis showed that patients who died early were older (56.2 +/- 15.6 vs. 42.1 +/- 10.4 years, p < 0.01), had lower serum creatinine (10.6 +/- 2.9 vs. 13.7 +/- 3.7 mg/dL, p < 0.01) and albumin (3.3 +/- 0.9 vs. 4.0 +/- 0.5 g/dL) and a higher urea/creatinine ratio (18.4 +/- 5.8 vs. 13.5 +/- 4.8, p < 0.01) compared with subjects surviving more than 10 years. Early death patients also had more cases of diabetes (35% vs. 0%, p < 0.01) and less chronic glomerulonephritis (9% vs. 35%, p < 0.05). Multivariate analysis showed that age (p < 0.01, CI 1.02 to 1.15, odds ratio 1.1) and urea/creatinine ratio (p < 0.01, CI 1.03 to 1.38, odds ratio 1.2) were positively and independently related to outcome. In the early death group, malnutrition was an important cause of death (17% of all deaths). Compared to baseline data, long-term survivors, at the last follow up, presented reduced systolic blood pressure and increased hematocrit and unchanged body weight, serum albumin and urea/creatinine ratio. These results, based on easily accessible initial variables, suggest that early death on dialysis is influenced by age and by indices related to the nutritional condition of the patients. They also highlight the importance of a potentially correctable risk factor in a population with an elevated prevalence of premature death.